AN APPROXIMATE SOLUTION CONSIDERING FLOW INERTIA BETWEEN SPHERICAL SURFACES

In this paper, the analytical expressions of the pressure distribution, velocity distribution and discharge of the flow between spherical surfaces are found by using the method of iterative approximate solution when the inertia terms of Navier-Stokes equations in spherical coordinates are taken into consideration. Furthermore, using these expressions, we can directly obtain the corresponding analytical expressions of the laminar radial flow between parallel disks, which are fully identical with corresponding results presented by refs.     

AN ANALYSIS ON THE FLOW RESISTANCE IN THE ENTRANCE REGION OF DIFFUSE LAMINAR FLOW BETWEEN TWO PARALLEL SPHERICAL SURFACES

In this paper.V.V.Golubef method is first extended to the diffuse laminar flowbetween two parallel spherical surfaces.With the boundary layer motion equation inspherical coordinates,we derive the momentum integral equation together with the energyintegral equation for the laminar boundary layer of the entrance region between twoparallel spherical surfaces.And then by applying Picards gradually approaching methodfor the momentum integral equation,we get the approximate expression which the entranceregion length varies with the thickness of boundary layer.In the end,every coefficient ofentrace region effect is analyzed and calculated.     

AN APPROXIMATE SOLUTION CONSIDERING FLOW INERTIA BETWEEN CONICAL SURFACES

In this paper, analytical calculation expressions of the pressure distribution, velocity distribution and the rate of the flow between conical surfaces are found by using the method of iterative approximate solution when the inertia terms of the Navier-Stokes equations in conical coordinates are taken into account. Furthermore, we compare the centrifugal flow with the centripetal flow of axisymmetrical passing flow.     

ON THE LINKING UP BETWEEN BINGHAM FLUID AND PLUGGED FLOW

When Bingham fluid is in motion, plugged flow often occurs at places far from theboundary walls. As there is not a decisive formula of constitutive relation for plugged flow,in some problems the solutions obtained may be indefinite. In this paper, annular flow andpipe flow are discussed,and unique solution is obtained in each case by utilizing the analyticproperty of shear stress. The solutions are identical in form with the commonly usedformula for the pressure drop of mud flow in petroleum engineering.     

THE TRANSIENT ELLIPTIC FLOW OF POWER-LAW FLUID IN FRACTAL POROUS MEDIA

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THE MOTION OF A SPHERICAL PARTICLE IN THE STOKES FLOW OUTSIDE A CIRCULAR ORIFICE

For any study of a suspension entering a pore,the knowledge of the force and momentexerted on a solute parficle in an arbitrary position outside the pore is essential.This paperfor the first time presents approximate analytical expressions(in closed form),of all thetwelve force and moment coefficients for a sphere outsied a circular orifice,on the basis of anumber of diserete data computed by Yan et al(1987),These coefficients are then appliedto calculate the trajectory and angular velocity of a spherical particle approaching the poreat zero Reynolds number.The trajectory is in excellent agreement with the availableexpermental results.An analysis of the relative importance of the coefficients shows thatthe rofation effect cannot be neglected near the pore opening or near the wall and that thelateral force effect must be taken into account in the neighborhood of the edge of the pore etlg"‘!/‘lh(‘pol‘eopening It is due to neglecting these factors that previous theoretical results deviate fromthe exper     

AN ANALYSIS OF THE EFFECTS OF THE PROSTATIC HYPERTROPY ON HE URINARY FLOW IN LOWER-URINARY-TRACT

In this paper an analytic model corresponding to the collapsible tube for analysing theurinary flow in lower-urinary-tract is set up from physiologic background.By analysing themodel it is found that the self-excited oscillations can both occur in the region of negativeand positive slope of P_n-Q_n characteristic. So this paper extends the results of ConradGriffiths,Conrad, Cohen and McQueen and others that the self-excited oscillationscan only occur in the region of negative slope of P_n-Q_n characteristic.The effects ofprostatic hypertropy on the flow parameters in lower-urinary-tract is discussed in detail bynumerical calculations.The results show that it is possible to know the conditions ofprostatic hypertropy according to the changes of bladder pressure, outlet urinary velocityand other parameters. From these results a theoretical method to detect and diagnoseprostatic hypertropy is provided.     

INVESTIGATION OF THE STABILITY FOR INVISCID COMPRESSIBLE SWIRLING FLOW BETWEEN CONCENTRIC CYLINDERS

The temporal stability on inviscid compressible swirling flow between two concntric cylinders is investigated. First. a linearized differential equation is derived. Two stbility criteria are derired for compressible swirling flow by an analytic method analogous to Ludwieg's method. A finite-difference numerical method is then used to solve the eigenvalue problem of this differential equation, to get temporal growth rate and to check these stability criteria derived. Finally, The effect of compressbility for stability is disscused.     

DUAL CHARACTERS OF INTERACTION BETWEEN PARTICLES AND FLUID

The unique characteristics of gas-solids two-phase flow and fluidization in terms of the flow structures and the apparent behavior of particles and fluid-particle interactions are closely linked to physical properties of the particles, operating conditions and bed configurations. Fluidized beds behave quite differently when solid properties, gas velocities or vessel geometries are vaded. An understanding of hydrodynamic changes and how they, in turn, influence the transfer and reaction characteristics of chemical and thermal operations by variations in gas-solid contact, residence time, solid circulation and mixing and gas distribution is very important for the proper design and scale-up of fluidized bed reactors. In this paper, rather than attempting a comprehensive survey, we concentrate on examining some important positive and negative impacts of particle sizes, bubbles, clusters and column walls on the physical and chemical aspects of chemical reactor performance from the engineering application point of view with the aim of forming an adequate concept for guiding the design of multiphase fluidized bed chemical reactors.     

A WEIGHTED PENALTY FINITE ELEMENT METHOD FOR THE ANALYSIS OF POWER-LAW FLUID FLOW PROBLEMS

In this paper,a new finite element method for the flow analysis of the viscousincompressible power-law fluid is proposed by the use of penalty-hybrid/mixed finiteelement formulation and by the introduction of an alternative perturbation,which isweighted by viscosity,of the continuity equation.A numerical example is presented toexhibit the efficiency of the method.     

An approximate solution considering flow inertia between spherical surfaces

In this paper, the analytical expressions of the pressure distribution, velocity distribution and discharge of the flow between spherical surfaces are found by using the method of iterative approximate solution when the inertia terms of Navier-Stokes equations in spherical coordinates are taken into consideration. Furthermore, using these expressions, we can directly obtain the corresponding analytical expressions of the laminar radial flow between parallel disks, which are fully identical with corresponding results presented by refs. [3,4].     

An approximate solution considering flow inertia between conical surfaces

In this paper, analytical calculation expressions of the pressure distribution, velocity distribution and the rate of the flow between conical surfaces are found by using the method of iterative approximate solution when the inertia terms of the Navier-Stokes equations in conical coordinates are taken into account. Furthermore, we compare the centrifugal flow with the centripetal flow of axisymmetrical passing flow.     

Transient flow towards a well in an aquifer including the effect of fluid inertia

Transient propagation of weak pressure perturbations in a homogeneous, isotropic, fluid saturated aquifer has been studied. A damped wave equation for the pressure in the aquifer is derived using the macroscopic, volume averaged, mass conservation and momentum equations. The equation is applied to the case of a well in a closed aquifer and analytical solutions are obtained to two different flow cases. It is shown that the radius of influence propagates with a finite velocity. The results show that the effect of fluid inertia could be of importance where transient flow in porous media is studied.List of symbols b Thickness of the aquifer, m - c ₀ Wave velocity, m/s - k Permeability of the porous medium, m² - n Porosity of the porous medium - p( ,t) Pressure, N/m² - Q Volume flux, m³/s - r Radial coordinate, m - r _w Radius of the well, m - s Transform variable - S Storativity of the aquifer - S _d(r, t) Drawdown, m - t Time, s - T Transmissivity of the aquifer, m²/s - ( ,t) Velocity of the fluid, m/s - Coordinate vector, m - z Vertical coordinate, m - Coefficient of compressibility, m²/N - Coefficient of fluid compressibility, m²/N - Relaxation time, s - (r, t) Hydraulic potential, m - Dynamic viscosity of the fluid, Ns/m² - Dimensionless radius - Density of the fluid, Ns²/m⁴ - (, ) Dimensionless drawdown - Dimensionless time - , x Dummy variables - ₀, ₁ Auxilary functions     

The analysis of stability of Bingham fluid flowing down an inclined plane

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Axisymmetric magnetohydrodynamic flow of micropolar fluid between unsteady stretching surfaces

This investigation examines the time dependent magnetohydrodynamic (MHD) flow problem of a micropolar fluid between two radially stretching sheets. Both strong and weak concentrations of microelements are taken into account. Suitable transformations are employed for the conversion of partial differential equations into ordinary differential equations. Solutions to the resulting problems are developed with a homotopy analysis method (HAM). The angular velocity, skin friction coefficient, and wall couple stress coefficient are illustrated for various parameters.     

An analysis on the flow resistance in the entrance region of diffuse laminar flow between two parallel spherical surfaces

In this paper, V.V. Golubef method is first extended to the diffuse laminar flow between two parallel spherical surfaces. With the boundary layer motion equation in spherical coordinates, we derive the momentum integral equation together with the energy integral equation for the laminar boundary layer of the entrance region between two parallel spherical surfaces. And then by applying Picards gradually approaching method for the momentum integral equation, we get the approximate expression which the entrance region length varies with the thickness of boundary layer. In the end every coefficient of entrace region effect is analyzed and calculated. Projects Suported by the Science Fund of the Chinese Academy of Sciences.     

滑滚表面间的流体膜壁面滑移和流体动力学

经典雷诺润滑理论建立在无壁面滑移的假设基础之上。近年来许多试验报告了发生在流体膜流动的壁面滑移证据。本文研究了两固体表面间的流体膜流动特性和流体动力学,发现壁面滑移显著影响膜的流体动力学问题,流体动压力不仅受黏度和几何间隙的影响,而且还由壁面滑移和表面运动强力控制,通过控制表面的吸附性质,甚至可以得到零摩擦表面。另一方面,如果两个表面具有相同的滑移特性,存在一个临界滑动速度使得流体动压效应完全消失;但是在纯滚动条件下,即使界面极限剪应力很小,仍然有相当可观的流体动压效应。